Photographic transfer process



Aug. 23, 1955 H. c.

YUTZY ET AL 2,716,059

PHOTOGRAPHIC TRANSFER PROCESS Filed Jan. 21, 1952 Fig.1

REFLEX EXPOSURE 4 UNHARDENED AgXEMl/LSION com/mus TAM/N6 AND NON-TANNING DE VELOPING AGENTS UNI-IA RDENED ALKALI DEVELOPMENT l TRANSFER HenryCi Yufzy Edwardfllizclcel INVENTORS United States Patent 0 PHOTOGRAPHIC TRANSFER PROCESS Henry C. Yutzy and Edward C. Yaclrel, Rochester, N. Y., assignors to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey Application January 21, 1952, Serial No. 267,447

7 Claims. (Cl. 956) This application is a continuation-in-part of our U. S. patent application Serial No. 783,914, filed November 4, 1947, now U. S. Patent 2,596,756, granted May 13, 1952.

This invention relates to photography and more particularly to a photomechanical copy method for use in the reproduction of printed matter.

There are a number of well-known photographic methods of reproducing designs such as printed matter on paper or other supports. For instance, by the so-called reflex copy method an emulsion layer is exposed through its support and the printed matter is reproduced as a negative. Or one may print a negative and a positive therefrom by conventional methods. In the photomechanical art a common practice is to expose a suitable photographic element such as a tissue and to transfer the exposed element to a metal plate after which the unexposed emulsion is washed off the plate or the Washing off may occur before transfer of the resist to the plate. Similarly, in the Pinatype process after forming a hardened image, colored matter is printed from the unhardened area of the element but the colloid vehicle is not transferred from that area to the printing surface. A limited amount of endeavor which has not been successful has been directed to a process wherein after exposing a dichromated albumen element, the unexposed and unhardened portion of the element is transferred to a second support.

In our mentioned invention is described a simple photographic method including difierentially hardening silver salt emulsion layers and transferring unhardened strata of such layers to a support to obtain useful images. In that process a substantially unhardened colloid-silver halide emulsion layer preferably containing a colloid tanning silver halide developing agent is exposed to a two-tone subject and after development in the presence of alkali a stratum of the unexposed region of the emulsion layer is transferred to a receiving sheet by merely pressing the sheet into contact with the developed emulsion layer and peeling off the sheet with a stratum of the unexposed region of the emulsion adhered thereto. The simplicity of the process is apparent when a comparison is made with other well'known reproduction methods such as those employing metal printing plates and which involve tedious etching steps. Other advantages reside in the fact that the silver halide sensitized materials are used, the superior properties of which are well known compared to elements sensitized by other means such as bichromated colloid layers.

In the mentioned process it was desirable that the stratum of emulsion obtained on the receiving sheet have sufficient optical density that it is readily visible. To that end, colored matter was either initially incorporated into the emulsion layer before exposure or subsequently was formed in the stratum of transferred emulsion layer, for example, by exposure of the transferred stratum to light followed by heating if desired to accelerate development of the silver halide in the stratum. Our above-mentioned invention also proposed for certain purposes to 2,716,059 Patented Aug. 23, 1955 incorporate into the substantially unhardened emulsion layer containing a tanning developing agent, a second developing agent such as a color developing agent.

We have discovered that if development of the exposed unhardened emulsion layer is carried out in the presence of not only a gelatin tanning silver halide developing agent but also in the presence of a nontanning or feebly tanning developing agent, either or both of which can be incorporated into the emulsion or the alkaline solution used in the development step, a process is provided which automatically provides the requisite reflection density for the region of the emulsion layer, a stratum of which is subsequently transferred to a receiving sheet. During development of regions of high exposure, sufiicient tanning development occurs to allow satisfactory insolubilization of the gelatin so that this region of the emulsion will not transfer to the receiving sheet. In those areas of the emulsion in which exposure is considerably less, corresponding to the shadows, such as printed matter in the subject, the silver halide is developed partly by both developing agents but tanning development is kept below a required minimum so that the gelatin in this area although slightly tanned is not sufliciently tanned to prevent transfer. The silver thus formed by tanning and 1 the nontanning development is sufficient to contribute very considerably to the density of the transferred image which constitutes an important advantage since no further treatment of the receiving sheet after transfer is necessary. The reduction of the degree of tanning in the relatively unexposed areas is also an advantage since it tends to allow transfer of those areas to the receiving sheet more easily.

When the process of this invention is applied to obtaining copy by exposing the unhardened emulsion layer to a subject such as printed matter by the reflex exposure method in which exposure is made through the support of the emulsion layer with the printed matter adjacent to the emulsion layer, a particularly valuable process is provided. In this method it is not advisable to incorporate any substantial amount of colored material such as dye pigments into the emulsion layer as these tend to prevent exposure through the emulsion from the base of the element. Accordingly, as can be seen by consideration of the drawings, when the emulsion layer contains both tanning and substantially non-tanning developing agents or the latter is in the alkaline solution used for development, the result of reflex exposure is that the emulsion is partially but uniformly exposed by the general exposure through the support, and areas of the emulsion layer corresponding to the highlights of the subject will receive appreciably more exposure than the areas corresponding to the shadows of the subject, and tanning development proceeds principally in the areas of the emulsion corresponding to the highlights in the subject although silver is formed throughout the emulsion layer. Similar effects are obtained when the exposure is made by other contact and projection printing methods.

The accompanying drawings show in greatly enlarged cross-sectional view a representation of the materials used at various stages in our process when the reflex exposure method is used. When other projection and contact printing methods are used for exposing the sensitive element, the development and transfer steps yield elements also appearing substantially as shown in Figs. 2 and 3 since these exposure methods also yield optical density in the emulsion layer in the regions corresponding to the shadows of the subject.

Our invention as applied to the reflex exposure method will now be described in more detail with particular solubility in the preferred range. pended claims, where the tanning developing agents are of silverihalide, 340 grams of gelatin and 5700 grams of water was jelled, noodled and washed for one-half hour 650 grams of 8% aqueous saponin solution 680 grams of dispersion A (a dispersion of 4-phenyl catechol prepared by dissolving 50 grams of 4-phenyl catechol in 75 grams of dibutyl phthalateat 80" C. and pouring it into a vigorously stirred solution of 50 grams of gelatin in 50 grams of 8% aqueous saponin solution and in 500 cc. of Water at 40 C.)

340 grams of a dispersion like A except substituting 4- methoxy-l-naphthol for 4-phenyl catechol This emulsion was coated over 500 square feet of paper containing no'ingredients tending to harden the emulsion. The emulsion on the paper base appears substantially as shown in Fig. l of the drawings wherein layer 11 is the emulsion layer carried by paper support 10.

- Examples of tanning developing agents especially useful because of nonwandering characteristics in emulsion layers are those having a solubility at 20 C. of from about .005 to".l.0 gram per 100 cc. of a phosphate-citric acid bulfer'solution of pH 5.0 prepared from a 1.5% solution 'mentioned diphenyl compounds are preferred because they possess the combination of the common properties, high rate of development, high tanning efficiency, and

Here, andin the apmentioned as incorporated in the emulsion, the desired I compounds are, for example, those mentioned and having the mentioned characteristics.

Otherwise, where tanning developing agents as hydroquinone and pyrocatechol, in absence of sulfite, are used, they are less desirable but useful results may be obtained. Compounds like 2- hydroxy-amino diphenyl or 3,4-diamino diphenyl are not especially useful because of their poor stability or failure. to tan." It'is, therefore, apparent that after exposure to a subject the differential hardening of the exposed emulsion can take place in the presence of a a tanning developing agent and that this includes whether or not the agent is in the emulsion before exposure.

The concentration of tanning or mixed tanning and non-tanning developing agents in the emulsion is dependent in part upon the result-desired but can be of the order of 350 grams'of developing agent per kg. of silver nitrate, converted to silverhalide, usedin making the emulsion to obtain good density,-or about 250 grams per kg. of silver nitrate to obtain adequate density and an emulsion having optimum keeping properties.

It is necessary for the successful operation of the invention that the emulsion layer be not harder than would be the case with gelatin containing 0.25 oz. of formalde-.

hyde (40%. diluted 1 to 3 with water) or 0.7 gram of dry formaldehyde per pound, when freshly coated; or 0.1 oz. of the solution per pound'for a sample aged three to six months. By substantially unhardened as used here,z and in the appended claims, it is to be understood that this means a hardness of the order obtained with gelatinv treated with. formaldehydeunder the conditions above. Emulsion layers appreciably harder will not transfer satisfactorily. Similarly, if, after development of the tanned image,'it is found that the layer is too hard, and'to accommodate variations in hardness and tanning encountered, 'we can use variations of temperature or pressure when making a transfer. we ordinarily apply pressure or temperature or both when rolling the. developed emulsion onto the receiving support.

In the emulsion in place of 4-methoxy-1-naphthol can To this end exposure the emulsion is hardened sufficiently during de-' be used other silver halide developing agents oxidation products of which formed during development of the gelatino silver halide emulsion layer are substantially incapable of tanning gelatin. Such other developing agents are N-methyl-p-aminophenol-x-sulfonic acid, p-

hydroxy anilinomethane sulfonic acid, pyrogallol dimethyl ether and 8-hydroxy-a-naphthol. These nontanning developing agents are preferably used in the emulsions in a a proportion of approximately to percent of total developing, agent, the balance of the developing agent, to percent, being the tanning developing agent.

. For copying by the reflex method, the subject 12 and emulsion layer 11 are arranged and exposed as shown in Fig. 1 of the drawings. The amount of exposure depends of course upon a number of factors such as the contrast of the subject, emulsion sensitivity and light source and should be regulated so that the regions 13 corresponding to the shadows of the subject are not unduly exposed. Exposure results in partially and uniformly exposing the emulsion with the light coming through the support, and latent images will be obtained in both areas 13 and 14' corresponding to the shadow and highlight regions respectively, the relative amounts of latent image obtained in these areas of the emulsion layer being dependent somewhat upon the contrast of the subject. when the exposed element is developed at F. sulficiently with an alkaline solution such as four'percent sodium carbonate solution containing sixpercent urea,

the result is to form silver throughout the emulsion layeras shown in Fig.2 of the drawings,.partly due to the image exposure and partly due to the general exposure through the support. In region 16 of the emulsion layer,

since exposureis less and therefore hardening is less,

the region will transfer, whereas in region 15 of greater velopment to prevent its transfer. It is preferred touse urea or other gelatin softener in the alkaline developing reflex exposure, development is'carried out by use of solutions of our invention to facilitate transfer of the stratum of unhardened emulsion. softeners such as formamide, ethylene chlorohydrin, and sodium nitrate can be used in the alkaline developing solution or in a separate solutionfollowing development in concentration of the order of 2 to. 20 percentto ac-Y commodate-variations which maybe encountered with different emulsions and conditions of' development.

and then pressed with the emulsion side next to an absorbent sheet such as paper 17 with the result that only the unhardened region 16 adheres to the sheetand when the sheet is peeled off,'only a thin stratum 18 of region 16 remains on the sheet as shown in Fig. 3. Additional copies of the subject can be made by merely re-moistening the emulsion layer 11 with alkaline solution and making transfers to sheets until the unhardened region 16 is exhausted. With insufficient exposure of the emulsion layer in the operation shown in Fig. l, the last copies may be lacking in desired optical density but of the tanning developing agentsuch as 4-phenyl catechol. After exposure by the selected method such as an alkaline solution containing one of the substantially nontanning silver halide developing agents, the development oxidation products of which have substantially no tendency to tan gelatin. Typical alkaline developer solutions useful contain four percent sodium carbonate, six percent urea and preferably containing not more than approximately the below-indicated concentrations .of any] With proper selection of exposure time,

Urea and other of, or weight proportion mixtures of, the following developiug agents:

G./liter 2,4diamino phenol 1.6 S-amino-Z-hydroxy toluene sulfate-.- 1.6 2,5-diamino toluene sulfate 1.6 p-Phenylenediamine r r 0.8 p-Aminophenol 1.6 p-Methylamino phenol sulfate 3.2 lso-ascorbic acid 3.2

useful results when used at temperatures of the order of 80 F.

Development by means of these developer compositions produces an element appearing substantially as shown in Fig. 2 of the drawings, the shadow regions of the emul sion layer containing silver and substantially unhardened gelatin and the other regions containing silver and hardened gelatin. As before, transfers of one or more strata of the unhardened area are made to suitable receiving sheets. Any of the methods disclosed in our application Serial No. 783,914 for further increasing optical density of the transferred stratum may of course be employed whether or not development has been carried out with alkaline solution containing the auxiliary developing agent.

It is to be noted that a particularly advantageous process results when the nontanning developing agent used in the emulsion layer is capable of coupling with itself during development with the alkaline solution. s-hydroxy-a-naphthol and 4-methoxy-a-naphthol are representative of such developing agents. Their use results in a dye being formed in the developed emulsion layer in both the shadow and highlight areas which adds to the density in the shadow region, strata of which are subsequently transferred to the receiving sheet.

What we claim is: l

l. A light-sensitive substantially unhardened gelatinosilver halide emulsion containing a mixture of a gelatin tanning silver halide developing agent of the class consisting of 3,4-dihydroxy diphenyl, 2,5-dihydroxy diphenyl and 2,3-dihydroxy diphenyl and a silver halide developing agent of the class consisting of N-methyl-p-aminophenol-x-sulfonic acid, p-hydroxy-anilino-methane sulfonic acid, pyrogallol dimethyl ether, 8-hydroxy-a-naphthol and 4-methoxy-a-naphthol, said emulsion being not harder than a gelatin layer containing 0.7 gram of formaldehyde per pound of gelatin freshly coated.

2. A method of photographic reproduction which comprises exposing to a two-tone subject a substantially unhardened gelatino-silver halide emulsion layer containing a mixture of a developing agent of the class consisting of 3,4-dihydroxy diphenyl, 2,5-dihydroxy diphenyl and 2,3-dihydroxy diphenyl, and a developing agent of the class consisting of N-methyl-p-aminophenol-x-sulfonic acid, p-hydroxy-anilino-methane sulfonic acid, pyrogallol dimethyl ether, 8-hydroxy-a-naphthol and 4- methoxy-u-naphthol, said emulsion layer being not harder than a gelatin layer containing 0.7 gram of formaldehyde per pound of gelatin freshly coated, developing the exposed emulsion layer with an alkaline solution to obtain a hardened gelatin and silver image in the region of exposure to the high-light area of the subject and substantially unhardened gelatin, silver and silver halide in the region of the emulsion layer corresponding to the shadow region of the subject, pressing a sheet having an 6 absorbent surface against said emulsion layer while said emulsion layer is moist to cause only the shadow region of the emulsion to adhere to said sheet, and separating said sheet and emulsion layer to transfer only a stratum of said shadow region of the emulsion layer to said sheet.

3. A method of photographic reproduction which comprises exposing to a two-tone subject a substantially unhardened gelatino-silver halide emulsion layer containing a mixture of approximately 60 to percent of the total developing agent, of a developing agent of the class consisting of 3,4-dihydroxy diphenyl, 2,5-dihydroxy diphenyl and 2,3-dihydroxy diphenyl, and approximately 40 to 35 percent of a developing agent of the class consisting of N-methyl-p-arninophenol-x-sulfonic acid, p-hydroxy-anilino-methane sulfonic acid, pyrogallol dimethyl ether, 8-hydroxy-wnaphthol and 4-methoxy-anaphthol, said emulsion layer being not harder than a gelatin layer containing 0.7 gram of formaldehyde per pound of gelatin freshly coated, developing the exposed emulsion layer with an alkaline solution to obtain a hardened gelatin and silver image in the region of exposure to the high-light area of the subject and substantially unhardened gelatin, silver and silver halide in the region of the emulsion layer corresponding to the shadow region of the subject, pressing a sheet having an absorbent surface against said emulsion layer while said emulsion layer is moist to cause only the shadow region of the emulsion to adhere to said sheet and separating said sheet and emulsion layer to transfer only a stratum of said shadow region of the emulsion layer to said sheet.

4. A light-sensitive substantially unhardened gelatinosilver halide emulsion containing a mixture of 3,4-dihydroxy diphenyl and 4-methoxy-a-naphthol, said emulsion being not harder than a gelatin layer containing 0.7 gram of formaldehyde per pound of gelatin freshly coated.

5. A method of photographic reproduction which comprises exposing to a two-tone subject a substantially unhardened gelatino-silver halide emulsion layer so as to obtain some exposure in the areas of the emulsion layer corresponding to the shadow areas of the subject and appreciably more exposure in the areas of the emulsion layer corresponding to the hightlight areas of the subject, said emulsion being not harder than a gelatin layer containing 0.7 gram of formaldehyde per pound of gelatin freshly coated, developing said exposed emulsion layer with an alkaline solution in the presence of both a gelatin tanning silver halide developing agent and a substantially non-tanning silver halide developing agent to obtain a hardened gelatin and silver image in the areas of the emulsion layer corresponding to the highlights of the subject, and substantially unhardened gelatin, silver and silver halide in the areas of the emulsion layer corresponding to the shadows of the subject, said development being such as to prevent any substantial tanning of the emulsion layer in said areas corresponding to the shadows of the subject, pressing a sheet having an absorbent surface against said emulsion layer while said emulsion layer is moist to cause only the shadow areas of the emulsion to adhere to the sheet, and separating said sheet and emulsion layer to transfer only a stratum of said shadow areas of the emulsion layer to said sheet.

6. The process of claim 5 wherein the gelatin tanning silver halide developing agent is present in the emulsion layer before exposure together with the substantially non-tanning silver halide developing agent.

7. The process of claim 5 in which the gelatin tanning silver halide developing agent is present in the emulsion layer before exposure together with a substantially nontanning silver halide developing agent which is capable of coupling with itself in the presence of alkali and exposed silver halide to form a dye.

(References on following page) References Cited in the file of this patept UNITED STATES PATENTS Eichengrun et a1. 2 Oct. 27, 1903. Albers et a1. Sept. 10, 1940 Knott Apr. 6, 1943 Rott June 20, 1944 Ryan et a1 Oct. 22, 1946 8 Yackel Apr. 8, 1952 Yackel May 13, 1952 Yutzy et a1 May 13, 1952 FOREIGN PATENTS 'France Mar. 2, 1942 Great Britaih Dec. 16, 1942 

2. A METHOD OF PHOTOGRAPHIC REPRODUCTION WHICH COMPRISES EXPOSING TO A TWO-TONE SUBJECT A SUBSTANTIALLY UNHARDENED GELATINO-SILVER HALIDE EMULSION LAYER CONTAINING A MIXTURE OF A DEVELOPING AGENT OF THE CLASS CONSISTING OF 3,4-DIHYDROXY DIPHENYL, 2,5-DIHYDROXY DIPHENYL AND 2,3-DIHYDROXY DIPHENYL, AND A DEVELOPING AGENT OF THE CLASS CONSISTING OF N-METHYL-P-AMONOPHENOL-X-SULFONIC ACID, P-HYDROXY-ANILINO-METHANE SULFONIC ACID, PYROGALLOL DIMETHYL ETHER, 8-HYDROXY-A-NAPHTHOL AND 4METHOXY-ANAPHTHOL, SAID EMULSION LAYER BEING NOT HARDER THAN A GELATIN LAYER CONTAINING 0.7 GRAM OF FORMALDEHYDE PER POUND OF GELATIN FRESHLY COATED, DEVELOPING THE EXPOSED EMULSION LAYER WITH AN ALKALINE SOLUTION TO OBTAIN A HARDENED GELATING AND SILVER IMAGE IN THE REGION OF EXPOSURE TO THE HIGH-LIGHT AREA OF THE SUBJECT AND SUBSTANTIALLY UNHARDENED GELATIN, SILVER AND SILVER HALIDE IN THE REGION OF THE IMULSION LAYER CORRESPONDING TO THE SHADOW REGION OF THE SUBJECT. PRESSING A SHEET HAVING AN ABSORBENT SURFACE AGAINST SAID EMULSION LAYER WHILE SAID EMULSION LAYER IS MOIST TO CAUSE ONLY THE SHADOW REGION OF THE EMULSION TO ADHERE TO SAID SHEET, AND SEPARATING SAID SHEET AND EMULSION LAYER TO TRANSFER ONLY A STRATUM OF SAID SHADOW REGION OF THE EMULSION LAYER TO SAID SHEET. 